A fully automatic pencil that continuously outputs lead is a writing instrument that ensures continuous output of lead to compensate for lead wear during the writing process. Its principle is to use the intermittent pressure during writing to press the lead core sleeve to move backward, and use the restoring force of the spring and the clamping force of the damping ring to pull out the lead core. As long as you press the key a few times, multiple lead cores in the lead core storage tube can be passed through the lead core tube, guide core tube, clip, and damping ring, and then sent to the lead core sleeve to replace the used lead cores, achieving continuous The purpose of transporting multiple lead cores. Unscrew the pencil head, and you will see a two-piece plastic piece covered by a metal ring. When you do not move, the metal ring covers the two plastic pieces, using friction to bite the lead core. When you move, , this part (the plastic piece in the metal ring) goes downward together. When it reaches a certain position, the metal ring is resisted and stops falling, while the plastic piece continues to fall. Because they are separated and the shapes are separated outward at a certain angle, in nature In this state, they cannot bite the lead core, so when they are released from the restraints of the metal ring, the lead core will fall without restraint, but only for a short distance. However, if you trigger the action, the pencil will rebound quickly, and the metal ring will cover the plastic. This is the principle, allowing the lead core to drop a small amount in a short period of time.